You can't predict the future, but you can prepare for it. In the off chance you get hurt in a car accident, take a nasty tumble, fall down a cliff, have a seizure, or get struck by lightning, it's always good to carry up-to-date information about your health in case you can't speak for yourself. A physical medical ID wallet card or bracelet can provide this information, but so can your iPhone.
The secret to this feature can be found in Apple's Health app in iOS 12, a great tool for keeping track of exercise stats, nutrition data, sleep activity, and more. In the Health app, you can set up a Medical ID on-screen "card" consisting of your most important health information that can help out first responders, nurses, doctors, and caregivers, as well as coworkers, family, friends, and even strangers.
While the feature has been available in the Health app since iOS 8, it's best to make sure you're running the newest iOS version possible, so update your iPhone if need be. Then, in the Health app, tap the "Medical ID" tab in the bottom right. On the following page, tap "Create Medical ID." If you already have one, tap "Edit" to make some changes, if necessary.
Note that you can also access the "Create Medical ID" and "Edit Medical ID" options under your own contact card from the Contacts or Phone app. You just need to pick your name, choose "Edit," then look for it at the bottom.
Once the editor is open, begin filling out information such as your full name, birthdate, medical conditions, allergies, medications, blood type — anything that is relevant to your health. Put own anything that could help in saving your life or making medical treatment smoother in an unforeseen health predicament.
For instance, if you're in an ambulance for an abnormally fast heart rate and get queasy, they may give you Phenergan to treat nausea. If you're allergic and can't speak to tell them, you could end up with idiosyncratic reactions that impair your mental and physical ability, which could complicate the whole reason you're there. Adding a reaction or allergy here can decrease the odds of this happening.
Aside from your health data, you can even tap "add emergency contact" to do just that; Choose a contact from the list, the best phone number, then establish your relationship to that contact. That way, if you end up in a hospital or someone finds you walking around confused, they can contact your emergency contact to notify them or find out what to do.
Before tapping "Done" to complete your Medical ID, make sure that "Show When Locked" is enabled at the top of this page under Emergency Access. This way, anyone that needs access to your information can bring up your Medical ID through your iPhone's lock screen (see next section).
None of the information entered in the Medical ID section is included in your Health Data tab in Apple Health or shared with any other apps, third-party or Apple-owned.
If you lock your iPhone, then wake it up, you won't find your new Medical ID on the lock screen. So what gives?
Apple doesn't place Medical IDs directly on the lock screen in iOS. Rather, your ID can be found in the lock screen's emergency call page. Get yourself to the passcode screen, tap "Emergency," then tap on "Medical ID." Your new Medical ID will appear with all the information you saved.
Medical ID comes in handy if you're able to move and think clearly but can't speak for some reason. Just pull up the Medical ID real quick and show it to whoever is treating you. However, this Medical ID is most useful to other people.
When you're unconscious, delirious, mentally unstable, or otherwise incapacitated, whoever is treating you or trying to find out information about you (like a contact) can pull up this data. But they might not know they can do this, and the only way they will is if you help spread the word right now.
If you need to delete the Medical ID for any reason, whether someone is borrowing your iPhone or it's now your significant other's — or whatever else the case may be — open up the "Medical ID" tab in Health. Tap "Edit," then "Delete Medical ID" at the bottom of the page. On the popup, confirm with "Delete Medical ID."